The present invention broadly relates to a length measuring device for threads wound onto a cross-wound package, especially textile threads, wherein a measurement device on the cross-wound package senses the diameter with a diameter sensor and senses each revolution with a revolution sensor.
In a length measuring device known from the German Pat. No. 3,143,451 the pivotable tube carrier is connected to a display device by means of a mechanical drive or the like. The momentary position of the indicator member of the indicator or display device is sensed by optoelectronic sensors and the signals are digitally processed in an electronic circuit. An inductively driven revolution sensor transmits a pulse to the electronic circuit at each revolution of the yarn or thread coil or package. The electronic circuit determines the length of the yarn or thread being wound up by each revolution from the signals provided to it by the sensors and further determines the total length of all of the yarn or thread wound up by means of integration. Upon attaining a prescribed length of wound-up yarn or thread, the winding process is interrupted. The full package is replaced by an empty bobbin tube and a new winding operation is initiated.